Novel Methods, let’s have a party in the Harvard Forest!

Wednesday, July 5, 2017, by Johnny Buck

Don’t you just love the emergence of plants in the spring or the changes in leaf coloring of trees in the fall? I’ve always admired the beauty and complexity of these events growing up. If you really pay attention to nature, you notice the first and last signs of insects at certain times of year, and when the migration of birds and animals happens. Do you notice the time of year your favorite fish are active and not active? These events are called phenologic events and the study of these events is called phenology. Phenology looks at the life cycles of the natural world and how they are influenced by changes in weather conditions.

I’m an Indigenous person from the U.S. and we continue to have strong connections to the land. For a few years now, my village on the mid-Columbia River in Washington State has observed and experienced extreme shifts of the growing seasons of various Native plants that are staple foods and medicines in our diet. This was most noticeable in the year 2015, when some of our plants’ growing seasons started significantly earlier and the duration of the growing season was noticeably shorter. This not only affects our diet, but the traditions, culture, and ceremonies associated with these native plants, foods, and medicines. This is what motivated me to pursue plant phenology research. The Harvard Forest Summer 2017 Research Program in Ecology has given me the opportunity to meet Andrew Richardson and work with two of his post-docs, David Basler and Margaret Kosmala.

The title of my group project is, “Explaining variation in the seasonal changes of trees.” To begin to do this, I’m using the PhenoCam network at the Harvard Forest. The PhenoCams are security cameras that are mounted on towers throughout the Forest, and they are programmed to take pictures of the tops of trees at various time intervals ranging from every fifteen minutes to every hour. These images are automatically processed and available on the PhenoCam website. PhenoCams provide trusted data, and you’ll find tens of thousands of images consistently taken of trees over the years, starting as early as 2008.

What can we learn from the images of PhenoCams? How can we use them as scientific data? These are two great questions. If you ever look at the images over time, you will notice when the leaves began to emerge for the deciduous trees in the forest and when they change color and fall off the trees. All the images have time stamps on them. An algorithm is applied to the PhenoCam images also, to produce a vegetation index. A vegetation index is just a value that measures the greenness of the trees. The vegetation index that we use is called a Gcc (green chromatic coordinate). The Gcc produces a bell curve of the growing season of trees. For the most part, the Gcc for all the trees in an image has been estimated. In my project, I am identifying individual trees, so I can get an individual Gcc for each of the 50 trees of my study. Extracting these sorts of details---rather than general patterns of “vegetation greenness” --- from PhenoCam images requires more work.

I am focusing on red oak and red maple trees. After identifying individual trees in PhenoCam images, I will locate and identify those trees out in the forest to collect various measurements of them. (This is one of the fun parts (short lived), where we use helium and party balloons out in the forest!) These attributes, such as species identity, tree size, and tree age, will then be related to the tree’s spring and autumn phenology as seen from the PhenoCams to better understand which are the important traits driving phenology. One of the outcomes expected is to find out if younger trees leaf out earlier than older trees.

The most interesting part of the project is working out in the field and collecting data. I get the opportunity to core and measure trees, develop novel methods to identify individual trees in the PhenoCam out in the field. Some of the software I get to work with is “R” studio and ArcGIS and GIMP 2.8. All of this is important work too, the research that I’m doing will help improve our understanding of individual tree phenology strategies, with this understanding, we can continue to improve our forest management practices and models associated with the relationships between trees and how much C02 they are taking up.

Johnny Buck is a rising senior at Northwest Indian College majoring in Native Environmental Science while earning prerequisites for Environmental Engineering. Upon completion of his undergraduate degree, he plans to continue his education in a joint program in Environmental Engineering and Law, concentrating in Environmental Law and Tribal Law. He hopes to lead teams in remediation, litigation and restoration efforts in the Northwest.